Tread surface for footwear



April 18, 1939.

H. T. KRAFT TREAD SURFACE FOR FOOTWEAR Filed April 1 1956 INVENTOR Herman T-Kraf't BY W 4 %6 ATTORNEYS Patented A r. 18,1939

PATENT OFFICE TREAD SURFACE FOR FOOTWEAR Herman T. Kraft, Akron, Ohio, assignor to The General Tire & Rubber Company, Akron, Ohio,

a. corporation of @hio Application April 1, 1936, Serial No. 72,020

Claims.

This invention relates to tread surfaces for footwear and particularly to soles and heels for footwear, and among itsobjects is the provision of new and improved soles and heels which will 5 have a maximum frictional contact with the floor or other surface, which will be extremely resilient and furnish a cushioning eifect for the wearer, and which will be simple in design, inexpensive to manufacture and of long wearing qualities.

Other objects will become apparent from a study of the specification and the drawing, in

' which:

Figure 1 is a side elevation of a shoe embody- 115 ing the sole and heel construction of this inven- Fig. 3, of a modification of the sole conflguration of this invention;

Fig. 6 is a modification of a sole construction with the ribs or vanes concentric; and

Fig. 7 is a modification of a heel construction corresponding to the sole construction of Fig. 6.

Briefly, my invention is embodied in soles or heels of molded rubber in which a plurality of closely spaced parallel or concentric, flexible and elastic finlike ribs of materially greater depth than width are employed. While the ribs are individually relatively weakand flexible, they F are sufficient in number to carry the loads to which they are normally subjected without substantial distortion. The ribs, however, provide an elastic cushion between the body of the sole or heel and the ground surface, which will yield in any direction under frictional thrusts exerted on the ground engaging edges of the ribs. The rubber in the traction surface of the sole or heel is maintained soft and pliable under all conditions of load and this greatly increases the adhesion of the sole or heel to the surface walked upon. It is this greatly increased non-sldd capacity of the sole and heel that renders the invention particularly useful in connection with athletic shoes.

Referring to the drawing by numerals of reference, l0 designates the sole and II the heel respectively of a shoe I 2. In a preferred embodiment of my invention the sole II) has a plurality of ribs I! of finlikeconstruction, separated by narrow grooves, or spaces 20, giving the bottom of the shoe a deep fluted appearance.

As shown in Fig. 2 these ribs are generally parallel to one another and extend substantially the entire length of the sole. In order to obtain a maximum frictional effect combined with great resiliency, it is important that these ribs be of 5 substantially greater depth than thickness as shown in Figs. 3 and 5. Around the periphery of the sole is a binding strip it which may be formed integrally with the sole, as shown in the drawing, and the ribs l3 may be joined to it at their extremities. The body portion ii of the outer sole which is fastened to the upper margin I6 and inner sole ll may be of any suitable thickness suflicient to serve as a backing for the ribs l3 which are formed integrally thereon. The thinnerthe body portion I5 is constructed the more resilient and pliable the sole will be.

It is proposed to extend the binding strip it which, as pointed out above, may be formed integrally with the sole somewhat above the normal level of the body portion Ill so as to provide the sole with a recessed upper surface into which the vamp of the shoe may be fitted. This construction will give added strength to the shoe and aid in preventing the sole from tearing loose from the vamp.

The construction of the heel is similar to that of the sole. The ribs l3, however, are made considerably deeper than-in the sole so as to give added height to the shoe, and a corresponding increase should be made in their thickness so that they will not be too unstable.

In Fig. 5 I have shown a modification of a shoe sole embodying my invention corresponding to the cross-section of Fig. 3. In this modification the fins or ribs l3 are similar to those shown in Fig. 3 except that the ribs l8 lying in a cen-, tral portion of a shoe are substantially deeper than those, I9, lying in the peripheral portion of the shoe sole. I

In the'modification of my invention shown in Fig. 6 the ribs or fins l3 instead of running in straight lines the length of the sole are formed concentrically one within another. However, they are still substantially of greater depth than width and the spaces between such ribs are relatively the same as described above for straight ribs.

In Fig. 7 is shown a modification of. a heel structure embodying this invention but instead of the ribs being in substantially straight lines as shown in Fig. 2 they are formed concentrically to correspond with the modified sole shown in Fig. 6.

In the manufacture of soles and heels embodying this invention any material which is sufliciently pliable, resilient and wear resisting (such as rubber) may be used. It will be seen that because of the yieldability of the individual ribs, a resilient sole is provided which tends to conform to the configuration of the surface over which the wearer is walking.

In constructing footwear embodying the present invention it is desirable that the ribs B be of the proper height or depth and thickness with regard to the substance out of which they are formed so that when a normal person for whom that particular footwear may be designed is supported on the sole the ribs l3 will not beexcessively deformed.

However, the ribs should be sufiiciently thin and flexible to yield under severe frictional thrusts exerted upon their ground engaging edges such as will be exerted when the wearer jumps, stops or turns quickly, as in running upon a gymnasium floor. This yielding action of the ribs provides a cushion between the shoe sole and floor which allows an appreciable relative movement between the body of the sole and the floor engaging edges of the ribs before the force of impact is checked by the frictional action of the ribs on the floor, thus increasing the resistance of the sole to slippage on the floor surface and reducing the strain on the ankle and foot of the wearer.

As pointed out above, the ribs or flutes comprising the configuration on the outer sole of a shoe or other footwear embodying this invention are relatively unstable. This is because they are substantially deeper than they are wide, and when a pressure is applied at an angle to the vertical axis of one of these flutes such flutes will not offer a great resistance to being deform ed. The ribs, however, do not completely collapse because, as pointed out above, the adjacent ribs are relatively close together and mutually interact to support one another under deformation.

Since the ribs or flutes are relatively thin and resilient they are somewhat extensible longitudinally and when a force is applied along one edge, such as when the person wearing the footwear makes a sudden stop, they will tend to extend themselves longitudinally and take up the sudden shock of stopping.

The ability of a shoe constructed according to 1 the present invention to cushion and partially absorb thrusts suddenly applied to its friction surface results in superior resistance to slipping and, since there is less sliding of the shoe on ground surfaces and less abrasion on the bottom surface of the shoe, the shoe has superior wear ing ualities.

Although several embodiments of the invention have been herein shown and described, it will be understood that numerous modifications of the construction shown may be resorted to without departing from the spirit of this invention as defined in the appended claims.

What I claim is:

1. A shoe tread portion comprising an elongated, laterally stable, binding strip that is continuous along" the periphery of said shoe tread portion, and a group of parallel, longitudinally extending, flexible flnlike ribs disposed within said peripherally extending binding strip, each of said flexible ribs being separated from each other by grooves and having flat, substantially parallel sides and being of materially greater depth than width and being laterally unstable and being disposed sufficiently close to each other to provide mutual support under compression and thrust.

2. A rubber shoe tread having a tread body provided with a normally convex road-engaging face having substantially thruout its width and length narrow, closely spaced ribs whichare longitudinally continuous, and which are substantially parallel and spaced by narrow rela-. tively deep, substantially parallel-sided grooves, said ribs being individually weak, elastic and flexible, but suflicient in number and in inter-supporting engagement to carry the weight of normal loads without substantial distortion, said ribs under load being normally straight but being capable of stretching and bowing to serpentive form when subjected to frictional thrusts directed longitudinally of said ribs.

3. A shoe tread of rubber comprising a body portion, a series of closely spaced substantially parallel resilient ribs formed integrally therewith, the ribs being of materially greater depth than thickness and separated from one another by grooves of less width than the effective width of the ribs, and a binding strip substantially continuous about the tread periphery, said binding strip having a ground-engaging edge substantially planar and flush with the ground-engaging edges of the ribs.

4. A shoe tread of rubber comprising a body portion, a series of closely spaced substantially parallel resilient ribs formed integrally therewith, the ribs being of materially greater depth than thickness and separated from one another by grooves of less width than the effective width of the ribs, a binding strip substantially continuous about the tread periphery and having a ground-engaging edge substantiallyflush with the ground-engaging edges of the ribs, and the ends of the ribs integrally secured into the side of the binding strip to reinforce the strip and the ribs.

5. A shoe tread of rubber comprising a body portion, a series of closely spaced substantially parallel resilient ribs formed integrally there- "with, the ribs being of materially greater depth than thickness and separated from one another by grooves of less width than the efiective width of the ribs, a binding strip substantially continuous about the tread periphery and having a ground-engaging edge substantially flush with the ground-engaging edges of the ribs, and the ends of the ribs integrally secured into the side of the binding strip to reinforce the strip and the ribs, the binding strip extending above the upper margin of the body portion to provide a peripheral band for attaching the tread to a shoe upper.

HERMAN T. KRAFT. 

